Methods for well completion



Oct. 17, 1967 N. A. scHUsTER 3,347,314

' METHODS FOR WELL COMPLETION Filed April 29, 1965 E 5 sheets-sheet 1 gg63 i. 26 60 7; .'I 23 45" 55 I; L 25 i0 f 47 Y f f f f f i l l 32 I l II JJ l 205 I I /l//C 0J ze/4 I INVENTOR.

. 1 l l /f/ l l Oct. 17, 1967 N A, SCHUSTER 3,347,314

METHODS FOR WELL COMPLETION Filed April 29, 1965 5 SheetS-Sheet 2 ZINVENTOR.

OC- 17, 1967 N. A. scHUsTER 3,347,314

METHODS FOR WELL COMPLETION Filed April 29, 1965 5 Sheets-Sheet 3 UnitedStates Patent O 3,347,314 METHDS FOR WELL CMPLETION Nick A. Schuster,Houston, Tex., assigner, by mesne assignments, to SchlumbergerTechnology Corporation, Houston, TeX., a corporation of Texas Filed Apr.29, 1965, Ser. No. 451,737 17 Claims. (Cl. 16o-13) ABSTRACT F THEDISCLOSURE This application discloses methods for consolidatingincompetent earth formations. More particularly, the disclosed methodsare directed toward consolidating incompetent earth formations andproviding iluid communication therewith of improved quality Without theattendant production of loose formation materials. These methods areaccomplished yby first perforating the particular formation beingcompleted in such a manner as to establish a circuitous flow passagetherein. Suitable fluids are then successively injected into one end ofthe circuitous flow passage as communication is established at its otherend with an enclosed chamber initially at a reduced or atmosphericchamber for flushing out debris in the ilow passage as well as loosenedformation particles to develop the ilow passage into an enlarged cavityin the formation. Once the chamber is filled, the injected fluidspermeate the formation adjacent to the enlarged cavity to stabilize orconsolidate the formation and maintain the integrity of the cavity.

Accordingly, as will subsequently become more apparent, this inventionrelates to methods for completing wells; and, more particularly, tomethods for inhibiting 'the production of sand from unconsolidated orincompetent subsurface formations.

The present trend in Well completion techniques is to rely upon only oneor, at most, a very few perforations at each of carefully selectedpoints in a well rather than indiscriminately scattering a large numberof perforations along a wide interval. Where such perforations are madeinto aparticularly loose or unconsolidated formation, sand particles andthe like will, however, be displaced into the well bore as connatefluids are produced from the formation. Thus, unless preventativemeasures are taken, these sand particles will either settle out andeventually fill the well bore or be carried to the surface by theproduced fluids and severely damage production equipment. Moreover, withonly a few perforations affording limited entry into the formation, theproduction will be severely limited should any of these perforations'become plugged.

Accordingly, to solve these problems, apparatus and methods have beendevised whereby as soon as a loose formation is perforated, a suitablebonding or consolidating agent is injected through the perforation intothe formation where, in time, it will react and harden. These agents orso-called plastics generally coat the sand particles and thereby cementthem together. Although it will depend upon the particular .agentsemployed, the pores spaces between -adjacent particles are left open inone Way or another so as to provide permeability. Thus, a portion of theformation surrounding the perforation is consolidated to serve as aporous support to prevent loose sand particles from entering theperforation as connate uids are produced from the formation.

Typical of such treating agents, apparatus and methods are thosedisclosed in Patent Nos. 3,153,449 granted to Maurice P. Lebourg and3,174,547 granted to Roger Q. Fields. As described in those patents, aperforating and injection -tool is positioned adjacent a formation thatis believed to be unconsolidated. An extendible Wall-engaging member isoperated to shift the tool toward one wall of the casing and sealinglyengage a sealing member on the opposite wall to isolate a portion of thewell bore from the well control fluids. A perforator, such as a shapedcharge, is then actuated to produce a perforation through the isolatedportion into the adjacent earth formations.

Thereafter, a bonding agent is ejected from a cylinder in the tool by adisplacing piston and ejected through the perforation into theformation.

The present invention is directed toward providing new and improvedmethods for injecting formation-consolidating materials intounconsolidated formations. In practicing the invention, shaped chargesare employed to produce a circuitous flow passage within the formation.When the shaped charges are detonated, however, they will depositlow-permeability debris Within the perforations and on their walls.Examinations have shown that this low-permeability debris includescasing and cement particles as well as residue products of the shapedcharges.

Thus, in the present invention, after the shaped charges are detonated,fluid communication is established through the circuitous ow passagebetween a low-pressure receiver and a source of treating agents at thehydrostatic pressure of the well control fluids. Connate fluids and thetreating agents will then flush the debris from the ow passage into thereceiver. When the receiver is filled, the formation-consolidating agentis injected through the cleaned passage into the formation.

Accordingly, it is an object of theI present invention to provide newand improved methods for obtaining flow passages into earth formationsthat are free of such obu jectionable low-permeability debris toincrease the ow rate at which treating agents can be injected into theformations as Well as the iiow rate at which connate fluids may besubsequently produced.

This and other objects of the present invention are provided by rstisolating adjacent surfaces in a well bore from the well control fluids;perforating through these isolated surfaces to provide a circuitousiiuid passage from one surface through the formation to the othersurface; flushing debris from the passage; and, thereafter, injectingtreating .agents into the passage.

A preferred form of apparatus to be used in practicing the new andimproved methods of the present invention is comprised of packing meansthat are selectively operable to isolate adjacent surfaces of an earthformation and cooperatively arranged with perforating means forproducing a circuitous ilow passage through the formation from onesurface to another as well as means for withdrawing debris from thepassage either before or concurrently With the injection of treatingagents into the passage.

The novel features of the present invention are set forth withparticularity in the appended claims. The present invention7 both as toits organization vand manner of operation together with Afurther objectsand advantages thereof, may best be understood by way of illustrationand example of certain embodiments when taken in conjunction with theaccompanying drawings, in which:

FIG. 1 is a view of one embodiment of a well completion tool Within awell bore and in position to practice the present invention;

FIG. 2 is an elevational view, partially in cross-section, of a portionof the tool depicted in FIG. 1;

FIGS. 3-5 are views depicting in sequence the apparatus of FIG. 1performing the methods of the present in- Ivention; and

FIGS. 6-8 are views depicting in sequence apparatus similar to thatshown in FIG. l practicing a variation of the present invention.

Turning now to FIG. 1, a well completion tool 10 is shown suspended froma multi-conductor cable 11 in a casing 12 secured within a borehole 13by a column of cement 14. The cable 11 is spooled from a winch (notshown) at the earths surface, with some of its conductors being arrangedfor selective connection to a conventional power source (not shown) andothers being connected to conventional indicating-and-recording means(not shown) at the surface of the ground.

The well completion tool is comprised of an elongated body 15 which, tofacilitate manufacture and assembly, may be arranged in tandemlyconnected sections. Longitudinally spaced, annular pack-off means orsealing members 16 and 17 are disposed on one side of the body 15 andextendible and retractable wall-engaging means 18 on its opposite side.

The upper portion of the body 15 encloses a hydraulic system (not shown)for selectively actuating the extendible wall-engaging means 13. Thishydraulic system may, for example, be of the type illustrated in PatentNo. 3,011,554 granted to Robert Desbrandes which utilizes thehydrostatic pressure of the well control fluids or mud 19 to develop anincreased pressure in the system for selectively actuating thewall-engaging means 18. Thus, upon command from the surface, thewall-engaging means 18 will be extended against one side of the casing12 to shift the tool 10 laterally and sealingly engage the sealingmembers 16 and 17 against the opposite side of the casing.

The hydraulically actuated wall-engaging means 18 are comprised of oneor more extendible pistons 2f) that support a back-up shoe 21 that isnormally held in a retracted position against the body 15 by springs 22.The pistons 20 are sealingly received within hydraulic cylinders (notshown) that are connected to the hydraulic system. Thus, whenever thehydraulic system is activated from the surface, the developed hydraulicpressure will urge the pistons 20 outwardly to extend the back-up shoe21 against the casing 12. Subsequently, the hydraulic system can bedeactivated to relieve the hydraulic pressure in the pistons so thatretraction of the shoe 21 can be effected. Inasmuch as the particulardetails of the hydraulic system and wall-engaging means 18 are notnecessary for fully understanding the present invention, they have beenshown only schematically in FIG. 1 to show their general functionsduring the practice of the present invention.

Separate treating agent cylinders 23 and 24 are formed in the lowerportion of the body 15 which may, for example, be arranged as disclosedin the aforementioned Lebourg and Fields patents. Thus, as described inthe Fields patent, the upper cylinder 23 sealingly receives a slidable,annular, piston member 25 that is sealingly engaged around aconcentrically positioned tubular 4member 26 that extends through theupper cylinder into the lower cylinder 24. The upper cylinder 23 isconnected by a centrally located passage 27 to a normally-closed valve28, such as that shown at 41 in Patent No. 3,121,459. A port 29 isprovided below the annular piston member 25 so that well control fluids19 can act upon the piston to displace a treating agent from thecylinder 23 through passage 27 whenever the valve 28 is opened.

The lower cylinder 24 is divided into separate compartments 30-32 byspaced, floating pistons 33-35 that are each fluidly sealed to the innerwall of the cylinder. As will be subsequently explained in greaterdetail, normallyclosed valves 36 and 37 in the floating pistons 33 and34 remain closed to segregate the treating agents in the chambers 30-32until each piston has reached its upper limit of travel. These pistons33 and 34 and valves 36 and 37 may be, for example, of the typeillustrated in FIG. 3 of the aforementioned Fields patent. A port 3S inthe lower end of the cylinder 24 admits well control fluids 19 into thespace below the lower piston 35. Thus, as described in greater detail inthe Fields patent, the hydrostatic pressure of the well control fluids19 acting on the lower piston will exert pressure on the treating agentsin the chambers .3U-32 to sequentially discharge the treating agentsfrom the chambers through the tubular member 26 and into a fluid passage39 thereabove which has a normally-open valve 40, such as at 105, in theabovementioned Desbrandes patent.

The passages 27 and 39 converge above their respective valves 28 and 40and are connected to a fluid passage 41 leading to the fluid dischargemeans 42. A pressure transducer 43 is -provided to continuously monitorthe pressure in the fluid passage 41. This transducer 43 may, forexample, be of the type shown in FIG. 9 of the Desbrandes patent and isconnected by an electrical lead (not shown) via the cable 11 to thepressure indicatingand-recording apparatus at the surface of the earth.Thus, by observing the variations in pressure measurements, an operatorcan determine the occurrence of various functions of the operating cycleof the well completion tool 10.

The fluid discharge means 42 include a pair of lateral chambers 44 and45 within the body 15 that are each open at one end, with the annularsealing members 16 and 17 being mounted around the open ends of thesechambers to provide central openings 46 and 47. The lower chamber 45 isconnected to fluid passage 41; and thin-walled closure members 48 and 49are mounted in the chamber on each side of the open upper end of thepassage to block the central opening 47 and the rearward portion of thechamber. A shaped charge 50 is received in the rearward portion of thechamber 45 and faces the closure members 48 and 49 so that, upondetonation, the perforating jet will puncture the closure members and bedirected through the central opening 47.

In a simil-ar manner, the upper chamber 44 is connected by a fluidpassage 51 to an enclosed low pressure or atmospheric chamber 52 in thebody 15. Thin-walled closure members 53 and 54 are mounted in the upperchamber 44 on each side of the open lower end of the passage 51 to blockthe central opening 46 of the sealing member 16 and the rearward portionof the chamber. A shaped charge 55 is disposed in the rear of thechamber 44 and directed toward the closure members 53 and 54 so that,upon detonation, the perforating jet will pierce the closure members andbe directed through the central opening 46. Suitable electricallyresponsive igniter means 56 and 57 (FIG. 2) that are `ignitable from thesurface of the earth via conductors in the cable 11, are connected tothe shaped charges 55 and 50.

It will be realized that when the shaped charge 50 is detonated topuncture the closure members 48 and 49 and produce a perforation into anearth formation, fluid communication will be established from the fluidpassage 41 through the central opening 47 and into the resultantperforation. Similarly, whenever the other shaped charge 55 isdetonated, the closure members 53 and 54 will be pierced and fluidcommunication will be established from the resultant perforation throughthe central opening 46 and into the low-pressure chamber 52.Accordingly, by detonating the shaped charges 50 and 55, a circuitouspassage (FIG. 3) will be produced in an adjacent earth formation thatextends between the central openings 46 and 47. Thus, debris that isdeposited in the circuitous passage can be swept into the low-pressurechamber 52 and treating agents may be injected into the fluid passageeither concurrently or shortly thereafter.

Turning now to FIG. 2, an elevational view, partially in cross-section,is shown of a preferred embodiment of the fluid discharge means 42, withreference numerals used in conjunction with FIG. 1 identifying thecorresponding elements. The shaped charge chambers 44 and 45 are formedin the body 15 by longitudinally spaced lateral bores that are tilted insuch a manner that their central axes 58 and 59 intersect a shortdistance in front of the forward ends of the bores. The shaped charges5) and 55 are secured and fluidly sealed in their chambers 45 and 44behind threaded tubular members 60 and 61 having enlarged-diameterflanges 62 and 63 on their forward ends. The flanges 62 and 63 supportmetal back plates 64 and 65 carrying the elastomeric sealing members 16and 17 and are received within forwardly facing counterbores 66 and 67in the body 15 and fluidly sealed therein by O-rings 68 and 69. O-rings70 and 71 around the central portions of the tubular members 60 and 61provide fluid-tight annular spaces 72 and 73 in the forward ends of thelateral chambers 45 and 44, with radial bores 74 and 75 connecting thesespaces to the central bores through the tubular members.

The thin-walled closure members 53 and 54 are spaced apart andthreadedly secured in the central bore through the upper tubular member61 on opposite sides of the radial bores 75 to block the central opening46 and isolate the shaped charge 55. The fluid passage 51 connects thespace between the thin-walled closure members 53 and 544 to an enlargedbore thereabove that is closed at its upper end to provide theatmospheric chamber 52. To detonate the shaped charge 55, detonatingmeans 56 are comprised of a short length of detonating cord 76 disposedon the rear of the shaped charge and coupled to a conventionalelectrical detonator 77 received within a transverse passage 78extending upwardly from the shaped charge chamber 44.

The other thin-walled closure members 48 and 49 are arranged in the same`manner and dene a space therebetween in the central bore of the lowertubular member 60 that is connected by the radial bores 74 to the mainfluid passage 41. The shaped charge 50 is detonated by detonating means57 comprised of a detonating cord 79 and electrical detonator 80. Thehydraulically actuated pistons 2l) are mounted in hydraulic cylinders inthe body with the back-up shoe 21 being normally retracted against therear face of the body.

Turning now'to FIGS. 3-5, the successive steps of the method of thepresent invention are schematically illustrated as they would beperformed by the well completion tool 10. Although the exact arrangementwill be determined by the particular consolidating materials to be used,a pre-flush fluid 81, such as a saline solution, is contained in theupper chamber 30 of the lower treating cylinder 24. The intermediatechamber 31 contains a plastic consolidation agent 82, such as a`formaline-cresol mixture, while the lower chamber 32 contains anafterflush agent 83, such as kerosene. A suitable temporary pluggingagent 84, such as Black Magic oil-base mud as supplied by Oil Base,Inc., of Compton, California, is deposited in the upper treatingcylinder 23.

After the treating agents 81-84 have been deposited in the cylinders 23and 24, the tool 1t? is assembled and positioned in a well bore 13adjacent a selected formation 85. By actuating the hydraulic system, theback-up shoe 21 is extended to shift the tool 1t) laterally andsealingly engage the sealing members 16 and 17 against -the casing 12.Once the sealing members 16 and 17 have been firmly seated, it will beappreciated that the central openings 46 and 47 in front of thethin-walled closure members 54 and 49 will be isolated from the wellcontrol fluids 19 in the well bore 13. By this time, the hydrostaticpressure of the well control fluids 19 will have displaced some of thepre-flush fluid 81 from the upper chamber 30 through the normally-openvalve 39 and into the space between the thin-walled closure members 53and 54.

The lower shaped charge 5) is then detonated to puncture the thin-walledclosure members 5.3 and 54 and produce a perforation S6 that is directedinto the formation 85 in a slightly upward direction. As the perforatingjet punctures the closure member 54, the hydrostatic pressure of thewell control fluids 19 (which are at a higher pressure than theformation fluids) will immediately displace preflush fluid 81 into theperforation 86. Then, as best seen in FIG. 3, when the other shapedcharge 55 is detonated to produce a second perforation 87 that eitherintersects the first perforation 86 or comes in close proximity thereto,flow communication will be established through the second perforationfrom the first perforation to the atmospheric chamber 52. Thus, bysuddenly opening communication from the formation 35 to the atmosphericchamber 52, the formation pressure will displace connate fluids andadjacent sand particles into the perforations 86 and $7 and on into theatmospheric chamber along with the pre-flush fluid 81. This suddenin-rush of the fluids will flush the debris from within theperforations. It will be appreciated that the sudden in-rush of thepre-flush fluid 81 may enlarge the perforations 86 and 87, as at 88, toprovide a still greater surface area for admitting other treatingagents. Chamber 52 is preferably of less volume than the volume of theupper chamber 30 for the pre-flush fluid 81.

Thus, as best seen in FIG. 4, once the pre-flush fluid 81 has beenexpelled from the upper chamber 30, the upper floating piston 33 willhave reached the top of the cylinder 24 to open the valve 36 therein.Then, the continued application of hydrostatic pressure on the lowerpiston 35 will displace the other treating agents 82 and 83 incontrolled sequence from the intermediate and lower chambers 31 and 32into the formation 35 where the consolidating plastic agent S2 willharden and, in time, consolidate the loose formation.

It should be understood that the detonation of the second shaped charge55 and opening of the formations to the low pressure chamber 52 causesboth the formation fluids and pressurized pre-flush agent 81 to flushany debris from the perforations. This flushing action which isprecipitated by detonation of the second shaped charge 55 can be at anyselected time during injection so long as the injection fluids areviscous enough to effect the desired removal of the aforementioneddebris.

i After closing the normally-open valve 40 by command from the surface,the normally-closed valve 28 is then opened. The hydrostatic pressure ofthe well control fluids 19 acting through the port 29 will then urge theannular piston 25 upwardly to displace the temporary plugging agent 84from the upper cylinder 23 into the perforations 86 and 87 or cavity 88.Agent 84 by filtration builds up a relatively impermeable surface whichprevents contact of the well control fluids with plastics in the cavity88 When the pack-off means 16 and 17 are removed.

Once all yof the treating agents 81-84 have been expelled from the tool10, the hydraulic system is actuated to relieve the hydraulic pressuretherein to retract the back-up shoe 21 and allow the tool to bewithdrawn from the well bore 13. The pressure of the well control fluids19 maintains the temporary plugging agent 84 in the cavity 88 while theplastic is setting.

The consolidation agents used in performing the present invention may beeither porous-setting or solid-setting plastics. The invention is notlimited, however, to any particular type of sand consolidating agent solong as it is capable of ultimately providing a porous barrier 89 withinthe formation around the perforation through which it is ejected.Typical types of sand-consolidation agents that may be used generallyinclude (1) a poroussetting type of plastic wherein a phase separationtakes place to leave hardened plastic around the sand grains and openpore spaces between the sand grains; (2) a porous-setting type ofplastic that shrinks and cracks upon setting to form openings within theconsolidating region to allow passage of connate fluids; (3) asolid-setting type of plastic wherein after the plastic is injected,after-flush fluids are injected to wash away the plastic from the porespaces between sand particles to provide sufficient permeability forflow of connate fluids; and (4) a solid-setting type of plastic whereinat least two of its constituents are kept separated from one anotherwithin the treating agent cylinder 24 and are sucessively injected intothe formation 85 to mix in situ. i

It will be further realized that the particular nature of thesand-consolidating agent employed will govern whether either a pre-flushor an after-Hush agent are required. Thus, the treating cylinder 24needs only to contain whatever agents or constituents thereof andarranged in whatever sequence that are considered to be necessary toobtain a porous consolidated portion, as at 89, that is calculated to besufficiently strong in time to prevent the collapse of the perforations86 and S7 and cavity 88. Therefore, the present invention should neitherbe considered as being limited to any particular one or genus ofsand-consolidating agents nor requiring pre-ii-ush or after-fiush fluidsunless necessary to achieve the abovementioned consolidating reaction.

Accordingly, it will be seen that to practice the method of the presentinvention, the tool is positioned in the borehole 13 adjacent to theformation 85 of interest. The sealing means 16 and 17 are urged againstthe casing 12 to isolate a surface thereon from the well control fluids19. Then, the formation 85 is perforated at spaced intervals, as at 86and 87, to produce a circuitous flow passage from one portion of theisolated surface to the other and provide flow communicationstherethrough from a source of a owable substance, such as a treatingagent, at an elevated pressure to a receiver at a lower pressure. Then,once the flowable substance has fiushed debris from the circuitous flowpassage, treating agents are injected into the formation 85. Thereaftera temporary plugging agent may be injected into the circuitous owpassage to prevent entry of the well control fluids 19.

Turning now to FIGS. 6-8, the successive steps of the present inventionare depicted las performed by a well completion tool 100 with a furtheroperational function. Inasmuch as the well completion tool 100 may bearranged in the same manner as the well completion tool 10 but with onlyminor additions, the same reference numerals employed in FIGS. 1-3 havebeen used in FIGS. 6-8 with prime marks thereafter to designate theequivalent elements and simplify the description of tool 100.Accordingly, it will be appreciated by comparison of the two groupsfigures that well completion tool 100 differs essentially from wellcompletion tool 10 only in that a second atmospheric chamber 101 isprovided that is connected to atmospheric chamber 52 by way of a fluidpassage 102 that is closed by a selectively-operable, normally-closedvalve 103.

After treating agents 01-84 have been deposited in the chambers 23 and24', thel tool 100 is assembled and positioned in a well bore 104 asseen in FIG. 6 adjacent a selected formation 105. `By actuating thehydraulic system, the back-up shoe 21 is extended to shift the tool 100laterally and sealingly engage the sealing members 16l and 17 againstthe casing 106. Once the sealing members 16 and 17 have been firmlyseated, it will be appreciated that the central openings in front of thethin-walled closure members 49 and 54 will be isolated from the wellcontrol fluids 107 in the well bore 104. At this time, the hydrostaticpressure of the well control fluids 107 will have displaced some of thepre-flush fiuids 81 from the upper chamber through the normally-openvalve 40 and into the space between the thin-walled closure members 48'and 49.

The lower shaped charge 50 is then detonated to puncture the thin-walledclosure members 118 and 49 and produce a perforation 108 that isdirected into the formation 105 in a slightly upward direction. As theperforating jet punctures the closure member 49', the hydrostaticpressure of the well control `fiuids 107 (which are at a higher pressurethan the formation fiuids) will immediately displace pre-flush fiuid 01into the perforation 108. Then, when the other shaped charge isdetonated to provide a second perforation 109 that either intersects thefirst perforation 108 or comes in close proximity thereto, uidcommunication will be established through the second perforation fromthe first perforation to the atmospheric chamber 52'. Thus, by suddenlyopening communication from the formation 105 to the atmospheric chamber52', the formation pressure will displace connate liuids and adjacentsand particles into the perforations 108, 109 and on into theatmospheric chamber 52 along with the pre-flush fluid 81. This suddenin-rush of fluids will flush the debris from Within the perforations. Itwill be appreciated that the sudden in-rush of the pre-fiush fiuid 81may enlarge the perforations and 109, as at 110, to provide a stillgreater surface area for admission of treating agents.

Thus, as best seen in FIG. 7, once the pre-ush fluid 81 has beenexpelled fom the upper chamber 30', the upper floating piston 33 willhave reached the top of the cylinder 24 to open the valve 36. Then, thecontinued application of the hydrostatic pressure on piston 3-5 willinject the other treating agents 82 and 83 in controlled sequence fromthe intermediate and lower chambers 31 and 32 and into the formation 105where, in time, the consolidating plastic agent 82 will harden andconsolidate the loose formation. Then, when the treating agents 82 and83l have been exhausted, valve 40 may be closed if desired and valve 28'opened. Opening of valve 2S' will admit the plugging agent 84 into thecavity 110 and allow it to infiltrate the formation 105 until arelatively impermeable filtrate layer has been built up on the cavitywalls.

To prevent collapse of the cavity 110, which might occur because offormation pressure equalization or of substantial overburden pressuresin a particularly unconsolidated formation, as seen in FIG. 8, a valve103 is then opened by command from the surface to exhaust the contentsof chamber 52' into the other atmospheric Chamber 101. This suddenexhausting of the contents of chamber 52 will, of course, allow aquantity of the plugging agent 84 to fiow through the Cavity 110 andinto the chamber 52. The flow of this final flushing will be maintainedby hydrostatic pressure and the plugging agent 84 will again form animpermeable filtrate layer. When the tool is removed, the hydrostaticpressure -acting on the plugging agent 84' in the cavity 110 willsupport the cavity and prevent well control fluids 107 from invading theformation 105. It should be understood, of course, that a valve, such asat 103, could also be used to control fluid cornmunication throughpassage 51 (and passage 51 in FIG. 1.

Once all of the treating agents 81-84 have been expelled from the tool100, the hydraulic system is actuated to relieve the hydraulic pressuretherein to retract the back-up shoe 21 and allow the tool to bewithdrawn from the well bore 104. After the porous support 111 about thecavity 110 has hardened, the pressure of the control fluids 19 can beremoved and production can be commenced. The pressure of formationfiuids when greater than the pressure within the casing, causes thetemporary plugging agent to be displaced into the casing 12.

Accordingly, it will be -seen that in the practice of the presentinvention, the tool 100 is positioned in the well bore 104 adjacent theformation 105. The sealing means 16 and 17 are urged against the casting106 and isolated adjacent surfaces thereon. These adjacent surfaces arethen perforated to provide a circuitous fiow passage through theformation 105 from one surface to the other and suddenly open the flowpassage to a rst atmospheric chamber, such as 52. Then, as iiuidsincluding a formation-consolidating agent, such as at 82', are injectedinto the passage, a cavity, such as at 110, will be cut in the formation105 and the debris washed into the chamber 52'. Theformation-consolidating agent 82' will be injected into the formation105 where, in time, it will firm and provide a hardened but poroussupport, such as at 111, around the cavity 110. Thereafter, by openingvalve 103, a second low-pressure chamber, such as at 101, is opened toflow the plugging agent, such as 84', through the cavity to form a fiowpassage. The plugging agent 84 will form an impermeable filtrate layeron the flow passage thru cavity 110. Then, after the tool 1t) iswithdrawn, the well control fluids lfi' will enter the cavity and, byvirtue of the filtrate layer, keep the flow passage from collapsing.

Thus, it will be appreciated that the present invention has provided newand improved methods for obtaining fluid passages into earth formationsthat are free of objectionable low-permeability debris so that materialsmay be injected into the formations at reasonably high flow rates. Itshould be noted that although the foregoing description was primarilydirected to the application of the methods of the present invention insand consolidation operations, these methods will be equally successfulin other completion operations where it is desired to inject flowablematerials into an ea-rth formation at reasonably high flow rates.

While particular embodiments of the present invention have been shownand described, it is apparent that changes and modifications may be madewithout departing from this invention in its broader aspects; and,therefore, the aim of the appended claims is to cover all such changesand modifications as fall within the true spirit and scope of thisinvention.

What is claimed is:

1. A method of completing a well bore traversing an earth formation,comprising the rsteps of: forming a first passage from the well boreinto the formation; forming a second passage from the well bore into theformation in a direction to intersect said first passage to be eectualfor establishing fluid communication therebetween; and, thereafter,lowering the pressure in the well bore below that in said passages forwithdrawing fluid through said passages to flush debris therefrom intothe well bore and enlarge said passages.

2. A method of completing a well bore traversing an earth formation,comprising the steps of: forming a first passage extending from the wellbore into the formation; forming a second passage directed from the wellbore into the formation and -substantially intersecting said firstpassage to be effectual for establishing fluid communicationtherebetween; and, thereafter, discharging fluid under pressure throughone of said passages while maintaining the other of said passages at alower pressure for flushing debris therefrom into the well bore andenlarging said passages.

3. A method of completing a well bore containing a column of Wellcontrol fluids and traversing an earth formation, comprising the stepsof: packing-off a portion of the well bore to isolate said portion fromthe well control fluids and from another portion of the well bore;perforating through one of said portions and into the formation toprovide a rst passage therein; perforating through the other of saidportions and into the formation to provide a second passage thereindirected relative to said rst passage to be effectual for establishingfluid communication therebetween; and, prior to unpacking said isolatedportion, discharging a fluid at one pressure from said other portionthrough said passages to said isolated portion while maintaining saidisolated portion at a reduced pressure for flushing debris therefrom.

4. A method of completing a well bore containing a column of wellcont-rol fluids and traversing an earth formation, comprising the stepsof: packing-off a portion of the well bore to isolate said portion fromthe well control fluids and from another portion of the well bore;perforating through one of said portions and into the formation toprovide a first passage therein; perforating through the other `of saidportions and into the formation to provide a second passage therein in adirection relative to said first passage to be effectual forestablishing fluid communication therebetween; and prior to unpackingsaid isolated portion, producing a pressure differential in the wellbore between said passages; and passing fluid through said passages intosaid isolated portion.

5. A method of completinga well bore containing a column of well controlfluids and traversing an earth formation, comp-rising the steps ofpacking-off a portion of the well bore to isolate said portion from thewell control fluids and from another portion of the well bore,perforating through one of said portions and into the formation toprovide a first passage therein, perforating through the other of saidportions and into the formation to provide a second passage thereinpositioned relative to said first passage to be effectual forestablishing fluid communication therebetween, and, prior to unpackingsaid isolated portion, coupling a receiver at a reduced pressure to saidisolated portion, said receiver being at a pressure calculated to besufficient to produce connate fluids from the formation, for flushingdebris from at least one of said passages and into the receiver.

6. A method of completing a well bore containing a column of wellcontrol fluids and traversing an earth formation, comprising the stepsof: packing-off a portion of the Well bore to isolate said portion ofthe well control fluids and from another portion of the Well bore;perforating through one of said portions and into the formation toprovide a first passage therein; perfo-rating through the other of saidportions and into the formation to provide a second passage thereinpositioned relative to said first passage to be effectual forestablishing fluid communication therebetween; prior to unpacking saidisolated portion, coupling a receiver vat a reduced pressure to saidisolated portion; and discharging a fluid at a greater pressure fromsaid other portion through said passages and into the receiver forflushing debris from said passages.

7. A method of completing a well bore containing a column of wellcontrol fluids and traversing an earth formation, comprising the stepsof: packing-off first and second portions of the well bore to isolatesaid portions from the well control fluids and from one another;perforating through one of said isolated portions and into the formationto provide a rst passage therein; perforating through the other of saidportions and into the formation to provide a second passage thereinpositioned relative to said first passage to be effectual forestablishing fluid communication therebetween; prior to unpacking saidisolated portion, coupling a receiver at a reduced pressure to one ofsaid isolated portions; and, thereafter, passing fluid from at least oneof said passages and into said receiver for flushing debris therefrom.

8. A method of completing a well bore containing a column of wellcontrol fluids and traversing `an earth formation, comprising the stepsof: packing-off first and second portions of the well -bore to isolatesaid portions from the well control fluids and from one another;perforating through one of `said isolated portions and into theformation to provide a first passage therein; perforating through theother of said portions and into the formation to provide a secondpassage therein positioned relative to said first passage to beeffectual for establishing fluid communication therebetween; coupling areceiver at a reduced pressure to one of said isolated portions and `asource containing a fluid at a greater pressure to the other of saidisolated portions; and, thereafter, discharging said fluid from saidsource through said passages and into said receiver for flushing debrisfrom said passages.

9. A method of completing a well bore containing a column of wellcontrol fluids and traversing an earth formation, comprising the stepsof: packing-off first and second portions of the Well bore to isolatesaid portions from the well control fluids and from one another;perforating through one of said isolated portions and into the formationto provide a first passage therein; perforating through the other ofsaid portions and into the formation to provide a second passage thereinpositioned relative to said first passage to be effectual forestablishing fluid communication therebetween; prior to unpacking saidisolated portion, coupling a receiver at a reduced pressure to one ofsaid isolated portions and a source containing -a fluid at a greaterpressure to the other of said isolated portions; discharging said fluidfromsaid source through said passages and into said receiver forflushing debris from said passages; and, thereafter, injecting atemporary plugging agent into said passages to isolate the exposedsurfaces therein from the Well control fluids.

if). A method of completing a Well bore containing a column of Wellcontrol fluids and traversing an earth formation, comprising the stepsof: packing-off first and second portions of the well bore to isolatesaid portions from the well control fluids and from one another;perfor-ating through one of said isolated portions and into theformation to provide a first passage therein; perforating through theother of said isolated portions and into the formation to provide asecond passage therein positioned relative to said first passage to beeffectual for establishing fluid communication therebetween; coupling areceiver at a reduced pressure to one of said isolated portions, saidreceiver being at a pressure calculated to be sufficient to produceconnate fluids from the formation, for flushing debris from saidpassages and into said receiver; coupling a source containing a fluid ata greater pressure to the other of said isolated portions; dischargingsaid fluid from said source through said passages and into said receiverfor flushing debris from said passages; and, thereafter, injecting atemporaryV plugging agent into said passages for isolating the exposedsurfaces therein from the well control fluids.

11. A method of completing a Well bore containing a column of Wellcontrol fluids and traversing an earth formation, comprising the stepsof: packing-off first and second portions of the Well bore to isolatesaid portions from the well control fluids and from one another;perforating through one of said isolated portions and into the formationto provide va first passage therein; perforating through the other ofsaid isolated portions and into the formation to provide a secondpassage therein positioned relative to said first passage to beeffectual for establishing fluid communication therebetween; coupling areceiver at a reduced pressure to one of said isolated portions and asource containing a treating agent at a greater pressure to the other ofsaid isolated portions; discharging said treating agent from said sourcethrough said passages for flushing debris from said passages and intosaid receiver and flowing into the formation when said receiver isfilled; and, thereafter, injecting -a temporary plugging agent into saidpassages for isolating the exposed surfaces therein from the wellcontrol fluids.

12. A method of completing a cased Well bore containing a column of Wellcontrol fluids and traversing an earth formation believed to includeunconsolidated particles comprising the steps of: packing-off first andsecond portions of the casing to isolate said portions from the Wellcontrol fluids and from one another; perforating through the casing atone of said isolated portions and into the formation to provide a firstpassage therein; perforating through the casing at the other of saidisolated portions and into the formation adjacent to said first passageto provide a second passage therein effective for establishing fluidcommunication with said first passage; coupling a receiver at a reducedpressure to one of said isolated portions and a source containing atleast a formation-consolidating fluid at a greater pressure to the otherof said isolated portions; and, then, discharging said fluid from saidsource into said passages for flushing debris from said passages intosaid receiver and, thereafter, into the formation for consolidating theunconsolidated particles when said receiver is filled.

13. A method of completing a cased well bore containing a column of Wellcontrol fluids and traversing an earth formation believed to includeunconsolidated particles comprising the steps of: packing-off first andsecond portions of the casing to isolate said portions from the Wellcontrol fluids and from one another; perforating through the casing atone of said isolated portions and into the formation to provide a firstpassage therein; 4perforating through the casing at the other of saidisolated portions and into the formation in a direction relative to saidfirst passage to provide a second passage therein effectual forestablishing fluid communication with said first passage; coupling areceiver at a reduced pressure to one of said isolated portions and asource containing a formation consolidating fluid at a greater pressureto the other of said isolated portions; and, discharging said fluid fromsaid source into said passages for flushing debris from said passagesinto said receiver and, When said receiver is filled, into the formationfor consolidating the unconsolidated particles.

lld. A method of completing a cased well bore containing a column ofwell control fluids and traversing an earth formation believed toinclude unconsolidated particles, comprising the steps of: packing-offfirst and second portions of the casing to isolate said portions fromthe well control fluids and from one another; perforating through thecasing at one of said isolated portions and into the formation toprovide a first passage therein; perforating through the casing at theother of said isolated portions and into the formation in a directioncalculated to approach an intersection with said first passage toprovide a second passage therein in fluid communication with said firstpassage; prior to unpacking said isolated portion, coupling a receiverat a reduced pressure to one of said isolated portions and a sourcecontaining a fluid and a formation-consolidating agent at a greaterpressure to the `other of said isolated portions; discharging said fluidfrom said source through said passages and into said receiver forflushing debris from said passages; and, then, discharging saidformation-consolidating agent into said passages for consolidating theformation particles.

15. A method of completing a cased well bore containing a column of Wellcontrol fluids and traversing an earth formation believed to includeunconsolidated particles, comprising the steps of: packing-off first andsecond portions of the casing to isolate said portions from the Wellcontrol fluids and from one another; perforating through the casing atone of said isolated portions and into the formation to provide a firstpassage therein; perforating through the casing at the other of saidisolated portions and into the formation in a direction calculated toapproach an intersection With said first passage to provide a secondpassage therein in fluid communication with said first passage; prior tounpacking said isolated portion, coupling a receiver at a reducedpressure to one of said isolated portions and a source containing afluid and a formation consolidating agent at a greater pressure to theother of said isolated portions; discharging said fluid from said sourcethrough said passages and into said receiver for flushing debris fromsaid passages; discharging said formation consolidating agent into saidpassages for consolidating the formation particles; and, then, injectinga temporary plugging agent into said passages to isolate the exposedsurfaces therein from the Well control fluids.

16. A -rnethod of completing a well bore containing a column of Wellcontrol fluids and traversing an earth formation, comprising the stepsof: positioning a source of treating fluid confined under pressure by afirst closure member opposite a first portion of the Well bore and areceiver maintained at a reduced pressure by a second closure memberopposite an adjacent second portion of the Well bore; packing-off rstand second portions of the Well bore to isolate said portions from theWell control fluids and from one another; perforating through said firstclosure member and first isolated portion and on into the formation forproviding a first passage therein and releasing said treating fluid intosaid first passage; perforating through said second closure member andsecond isolated portion and on into the formation, in a directioncalculated to approach an intersection with said first passage, forproviding a second passage in the formation and opening fluidcommunication between said receiver and rst passage; and then,discharging said treating Huid from said source through said passagesand into `said receiver for ushing debris from said passages.

17. A method of completing a well bore containing a Icolumn of wellcontrol uids and traversing an earth formation, comprising the steps of:positioning a source of treating uid confined under pressure by a firstclosure member opposite a rst portion of the well bore and a receivermaintained at a reduced pressure by a second closure member opposite anadjacent second portion of the Well bore; packing-off said rst andsecond portions of the Well bore to isolate said portions from the Wellcontrol fluids and from one another; perforating through said rstclosure member and first isolated portion and on into the formation, ina direction calculated to approach the intersection with said rstpassage, for providing a second passage in the formation and openingfluid communication between said receiver and rst passage; dischargingsaid CTI treating duid from said source through said passages and intosaid receiver for flushing debris from said passages; and, then,injecting a temporary plugging agent into said passage to isolate theexposed surfaces therein from the Well control uids.

References Cited UNITED STATES PATENTS 2,237,313 4/1941 Pmaon 166-132,321,256 1/1958 Boiler 166- 100X 3,115,932 12/1963 Reynokis 166 23X3,121,459 2/1964 van Ness et a1. 16623 X 3,182,722 5/1965 Reed 166w-253,212,576 10/1965 Lannion 175-4.52X 3,277,961 10/1966 Bohn 166 -35X3,289,764 12/1966 santourian 166-42 CHARLES E. OCONNELL, Prim'aryExaminer. DAVID H. BROWN, Examiner.

1. A METHOD OF COMPLETING A WELL BORE TRAVERSING AN EARTH FORMATION,COMPRISING THE STEPS OF: FORMING A FIRST PASSAGE FROM THE WELL BORE INTOTHE FORMATION; FORMING A SECOND PASSAGE FROM THE WELL BORE INTO THEFORMATION IN A DIRECTION TO INTERSECT SAID FIRST PASSAGE TO BE EFFECTUALFOR ESTABLISHING FLUID COMMUNICATION THEREBETWEEN; AND, THEREAFTER,LOWERING THE PRESSURE IN THE WELL BORE BELOW THAT IN SAID PASSAGES FORWITHDRAWING FLUID THROUGH SAID PASSAGE TO FLUSH DEBRIS THEREFROM INTOTHE WELL BORE AND ENLARGE SAID PASSAGES.